Systems and methods for break detection

ABSTRACT

A system for detecting a failure along a transmission line of a cable plant is provided. The system includes a mobile vehicle configured to travel along a pathway substantially proximate to the cable plant along a span of the transmission line, and a transmitter disposed with the mobile vehicle. The transmitter is configured to emit (i) a test signal capable of ingressing the transmission line at a location of the failure, and (ii) an information signal containing location and velocity data of the mobile vehicle. The test signal is configured to provide phase shift and Doppler frequency information to a receiver operably connected to the transmission line at a location upstream from the location of the failure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/155,866, filed on Oct. 9, 2018. U.S. application Ser. No. 16/155,866claims the benefit of and priority to U.S. Provisional PatentApplication Ser. No. 62/569,645, filed Oct. 9, 2017. All of these priorapplications are incorporated herein by reference in their entireties.

BACKGROUND

The field of the disclosure relates generally to data transmissionsystems, and more particularly, to data transmission systems utilizingdefect testing on data transmission lines.

Conventional transmission systems cable operators experience a problemwith aging cable lines that, over time, experience a variety of faults.A shield break in the cable line, for example, is a fault producing adiscrete reflection from one point in the line. Other faults, such aswater seeping into the cable, will increase signal attenuation throughthe cable, even if the seepage only sometimes produces reflections. Inan outdoor environment, the cable line is typically copper or fiber, andmay be planted (i.e., a cable plant) as aerial cable between poles, inan underground conduit system, or by direct burial. However, whetheraerial or buried, cable shields and splices eventually fail due toenvironmental conditions, causing degraded subscriber quality ofexperience or signal outage.

When a cable plant experiences transmission difficulties, thequestionable cable line must be assessed for the line quality. That is,the line must be checked for faults due to problems such as shieldbreaks, water damage, stress fractures, corrosion, bad connectors,failed splices, animal chews, or other mechanical damage. Thefailing/failed line may exhibit excessive attenuation, reflections, orboth. The line will typically also be checked to determine if there hasbeen an attempt to cut into the line for signal sharing, such as from anillegal tap. Conventional testing schemes typically perform a “truckroll” to locate the source of the failure, and then replace the failedportion of the cable. In a truck roll, a moving vehicle travels alongthe cable plant to measure the signal proximate the cable, and attemptto capture the leakage from the source of the failure.

Cable operators have long used truck rolls to detect signal leakage inlower frequency bands. For example, in systems using amplifier cascadeswith diplex filters, only signals within the 5-42 MHz range are able totravel back to the fiber node. However, more recently, many cable plantshave been experiencing significant signal leakage in the UHF spectrum(e.g., typically between 300 MHz and 3 GHz), which may interfere withCATV services, as well as other services, such as long term evolution(LTE) communications. The long wavelengths of the lower frequencies,which conventional truck roll techniques measure, are not generallyuseful for accurate leakage location at these higher UHF frequencies.Additionally, a conventional truck roll requires use of measuringequipment having substantial weight, and which may not easily be carriedby a human technician, or mounted on an aerial surveillance vehicle(e.g., a drone).

BRIEF SUMMARY

In an embodiment, a system for detecting a failure along a transmissionline of a cable plant is provided. The system includes a mobile vehicleconfigured to travel along a pathway substantially proximate to thecable plant along a span of the transmission line, and a transmitterdisposed with the mobile vehicle. The transmitter is configured to emit(i) a test signal capable of ingressing the transmission line at alocation of the failure, and (ii) an information signal containinglocation and velocity data of the mobile vehicle. The test signal isconfigured to provide phase shift and Doppler frequency information to areceiver operably connected to the transmission line at a locationupstream from the location of the failure.

In an embodiment, method is provided for detecting a shield break alonga cable line by a mobile vehicle. The method includes a step oftraveling along a span of the transmission line at a first velocitywithin a detectable proximity to the transmission line. The methodfurther includes a step of transmitting, during the step of traveling,(i) a test signal capable of entry into the transmission line at theshield break, and (ii) a periodic information signal containing updatedlocation and velocity information about the mobile vehicle. The methodfurther includes a step of receiving, through the transmission line fromthe shield break, the test signal. The method further includes a step ofanalyzing the received test signal together with the updated locationand velocity information from the information signal to determine aDoppler frequency spectrum of the mobile vehicle with respect to thetransmission line.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the following accompanyingdrawings, in which like characters represent like parts throughout thedrawings.

FIG. 1 is a graphical illustration depicting a break detection system inaccordance with an embodiment.

FIG. 2 is a graphical illustration depicting a frequency distributionthat may be received according to operation of the break detectionsystem depicted in FIG. 1 .

Unless otherwise indicated, the drawings provided herein are meant toillustrate features of embodiments of this disclosure. These featuresare believed to be applicable in a wide variety of systems including oneor more embodiments of this disclosure. As such, the drawings are notmeant to include all conventional features known by those of ordinaryskill in the art to be required for the practice of the embodimentsdisclosed herein.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a,” “an,” and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about,” “approximately,” and “substantially,” are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged; such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

As used herein, the terms “processor” and “computer” and related terms,e.g., “processing device”, “computing device”, and “controller” are notlimited to just those integrated circuits referred to in the art as acomputer, but broadly refers to a microcontroller, a microcomputer, aprogrammable logic controller (PLC), an application specific integratedcircuit (ASIC), and other programmable circuits, and these terms areused interchangeably herein. In the embodiments described herein, memorymay include, but is not limited to, a computer-readable medium, such asa random access memory (RAM), and a computer-readable non-volatilemedium, such as flash memory. Alternatively, a floppy disk, a compactdisc—read only memory (CD-ROM), a magneto-optical disk (MOD), and/or adigital versatile disc (DVD) may also be used. Also, in the embodimentsdescribed herein, additional input channels may be, but are not limitedto, computer peripherals associated with an operator interface such as amouse and a keyboard. Alternatively, other computer peripherals may alsobe used that may include, for example, but not be limited to, a scanner.Furthermore, in the exemplary embodiment, additional output channels mayinclude, but not be limited to, an operator interface monitor.

Further, as used herein, the terms “software” and “firmware” areinterchangeable, and include any computer program storage in memory forexecution by personal computers, workstations, clients, and servers.

As used herein, the term “non-transitory computer-readable media” isintended to be representative of any tangible computer-based deviceimplemented in any method or technology for short-term and long-termstorage of information, such as, computer-readable instructions, datastructures, program modules and sub-modules, or other data in anydevice. Therefore, the methods described herein may be encoded asexecutable instructions embodied in a tangible, non-transitory, computerreadable medium, including, without limitation, a storage device and amemory device. Such instructions, when executed by a processor, causethe processor to perform at least a portion of the methods describedherein. Moreover, as used herein, the term “non-transitorycomputer-readable media” includes all tangible, computer-readable media,including, without limitation, non-transitory computer storage devices,including, without limitation, volatile and nonvolatile media, andremovable and non-removable media such as a firmware, physical andvirtual storage, CD-ROMs, DVDs, and any other digital source such as anetwork or the Internet, as well as yet to be developed digital means,with the sole exception being a transitory, propagating signal.

Furthermore, as used herein, the term “real-time” refers to at least oneof the time of occurrence of the associated events, the time ofmeasurement and collection of predetermined data, the time for acomputing device (e.g., a processor) to process the data, and the timeof a system response to the events and the environment. In theembodiments described herein, these activities and events occursubstantially instantaneously.

FIG. 1 is a graphical illustration depicting a break detection system100. System 100 includes at least one mobile detection vehicle 102. Inthe exemplary embodiment illustrated in FIG. 1 , mobile detectionvehicle is depicted as a land-based automobile (e.g., a truck)configured to perform a truck roll. This example is provided for ease ofexplanation, but is not intended to be limiting. As described furtherherein, in some embodiments, mobile detection vehicle 102 may beaerial-based (e.g., a plane, drone, etc.). In other embodiments, mobiledetection vehicle 102 may represent an electronic device being carriedby a person at walking speeds.

In this example, vehicle 102 is further depicted to travel along adirection A that substantially follows a pathway 104 of a cable plant106, at a substantially perpendicular separation distance Y from cableplant 106. In this example, cable plant 106 is depicted as an outdooraerial plant, but may also be a buried plant, an indoor plant, oranother known cable line distribution. Cable plant 106 includes at leastone cable line 108 in operable communication with (e.g., physicallyconnected to) at least one node or hub site (not shown in FIG. 1 ).Cable line 108 may, for example, be a coaxial cable, a twisted-pairline, or a communication fiber. Cable line 108 includes a shield break110 along pathway 104.

In the exemplary embodiment, vehicle 102 includes a first transmitter112 configured to emit a continuous wave (CW) radio frequency (RF) testsignal 114. Vehicle 102 may further include a second transmitter 116configured to emit an RF informational signal 118. RF informationalsignal 118 may, for example, include information pertaining to thelatitude, longitude, velocity, and direction of vehicle 102 at any givenmoment in time. In an exemplary embodiment, RF information signal istransmitted continually, at frequent periodic intervals (e.g., 10-100times/second). In the example depicted in FIG. 1 , first and secondtransmitters 112, 114 are shown to be separate and distinct elements. Inat least one embodiment, first and second transmitters 112, 114 are thesame element, which is configured to transmit both test signal 114 andinformational signal 118. In some embodiments, vehicle latitude andlongitude, as well as vehicle velocity, may be obtained from a GPSdevice (not separately shown) disposed in or on vehicle 102.

In exemplary operation of system 100, vehicle 102 travels in direction Asubstantially along pathway 104 and emits RF a CW test signal 112 withina detectable vicinity of cable line 108. As vehicle approaches thephysical location of shield break 110, test signal 112 is picked up byshield break 110 and will travel upstream of cable line 108 (i.e., withrespect to a downstream transmission from the cable operator) toward thenode/hub (e.g., a fiber node, a modem termination system (MTS) or cableMTS (CMTS), an optical line terminal (OLT), etc.). A receiver (not shownin FIG. 1 ) at, or in operable communication with, the node/hub may thenanalyze the frequency spectrum of test signal 112 over time for phaseshift information and Doppler frequency information over time. Anexemplary frequency plot is illustrated below with respect to FIG. 2 .

FIG. 2 is a graphical illustration depicting a frequency distribution200 that may be received according to operation of break detectionsystem 100, FIG. 1 . In the exemplary embodiments depicted in FIG. 2 ,distribution 200 is illustrated with respect to a first frequency plot202 and a second frequency plot 204, with both first and secondfrequency plots 202, 204 represented as a function of distance of travelby vehicle 102 in direction A. In the exemplary embodiment, firstfrequency plot 202 indicates a case of vehicle 102 travels at arelatively constant separation distance Y from pathway 104, and secondfrequency plot 204 indicates a case of vehicle 102 traveling at asignificantly greater separation distance Y′ from pathway 104.

Further to the example depicted in FIG. 2 , first frequency plot 202 isillustrated to shift more abruptly and precipitously about a point 206corresponding to break location 110, whereas second frequency plot 204is illustrated to flow more smoothly about the same point 206. Thesedifferent curve shapes may occur, for example, in the case where vehicle102 is traveling at relatively high speeds (e.g., smooth curve of secondfrequency plot 204), and at relatively slower speeds (e.g., sharpercurve of first frequency plot 202). For ease of explanation, plot 202,204 illustrated cases of vehicle 102 traveling at substantially constantvelocities and separation distances Y from cable plant 106. In actualpractice, the velocity of vehicle 102, as well as its separationdistance Y from cable plant 106, are expected to vary over a truck rolloperation.

Accordingly, in the exemplary embodiment, vehicle 102 travelssubstantially along pathway 104 and emits RF CW test signal 112, whichis picked up by cable line 108 at shield break 110, and travels upstreamtoward the node (or hub) where test signal 112 is received and analyzedfor phase shift and Doppler frequency over time and distance. In theexemplary embodiment, vehicle 102 further admits RF information signal118 indicating the latitude, longitude, velocity, and/or direction A ofvehicle 102 at the time of broadcast (e.g., 10-100 times/sec). At thereceiver, test signal 112 and information signal 118 are received andanalyzed for the source location and the point of Doppler shift, asindicated in FIG. 2 .

In some embodiments, the emission and coordinated analysis of signals112, 118 at the receiver are similar in some respects to syntheticaperture radar (SAR) and inverse SAR (ISAR) techniques, but may beperformed in a significantly simplified and advantageous manner. Thatis, SAR/ISAR are techniques, typically employed in high-speed aircraftand space-based probes and satellites, using radar imaging to generatehigh resolution images of a target. ISAR technology utilizes themovement of the target to create a synthetic aperture, whereas SARutilizes the movement of the emitter, somewhat in the matter of thepresent embodiments. SAR systems, however, employ beamforming to aim asignal in a direction perpendicular to the path of system travel. Incontrast, the present embodiments do not require beamforming foremission of either signal 112, 118.

The innovative techniques of the present embodiments are therefore ofparticular advantage use with respect to newer fiber deep and N+0architectures, where UHF signals may propagate back to the fibernode/hub site. As described above, systems using amplifier cascades withdiplex filters only permits signals in the 5-42 MHz range to travel backto fiber node, and these longer wavelengths are therefore not useful foraccurate leakage location as UHF frequencies.

In the exemplary embodiments illustrated herein, processing of signals112, 118 are described as being processed at the node or hub site.However, the person of ordinary skill in the art will understand, afterreading and comprehending the present description and drawings, thatsignal reception, processing, and analysis are not limited to theselocations only. For example, reception and/or processing may beperformed by a processor (not shown) installed within vehicle 102 (e.g.,a separate processing unit programmed with executable instructions, ahandheld device with adequate processing power, etc.).

Furthermore, signals 112, 118 may be transmitted from separatetransmitters or antennas, or may be transmitted from the sametransmitter or antenna. In some embodiments, either or both of signals112, 118 may be transmitted from more than one antenna/transmitter wheresome redundancy may be desired.

In an exemplary embodiment, system 100 is configured to transmitinformation signal 118 substantially in real-time. In other embodiments,vehicle 102 may be configured to include at least one memory unit/device(not shown) capable of storing precision timestamps of the continuallatitude/longitude data of vehicle 102, which then may be downloaded atthe receiver and matched with data of test signal 112, which may arriveseparately.

The present systems and methods are described herein with respect to CWRF signals, but these signals are also provided by way of example, andare not intended to be limiting. Other types of signals may be used,such as those capable of being analyzed for phase information (e.g., CWchirps, pseudo-noise (PN) sequences, etc.). In some embodiments, testsignal 112 is transmitted at a single frequency. In other embodiments,test signal 112 is transmitted as a plurality of signals and/or atmultiple frequencies at a time (e.g., 139 MHz, 400 MHz and 800 MHz).

The present systems and methods are particularly advantageous withrespect to the mode of application as well. That is, the presentembodiments represent a significant improvement to a conventional truckroll technique on a cable plant, with respect to both the efficiency andaccuracy of the truck roll. Nevertheless, the techniques describedherein are also significantly advantageous for use by, for example, atechnician on foot testing an individual house or building, as well asan individual span of a cable line. In at least one embodiment, thetechnician is able to employ the present embodiments at a plant locationwhile on foot, and receive a leakage report from the headend/hub on ahandheld mobile device (e.g., smart phone). The present techniquestherefore useful in not only coaxial cable embodiments, but also forsystems employing twisted-pair transmission lines, or other non-coaxialtransmission media, and for both indoor and outdoor plants.

The present systems and methods therefore represent significant advancesover conventional techniques. Conventional leak detection systems, forexample, may not be easily configured to operate two separate antennasfrom the detection vehicle, due to the risk of creating a false image.The present embodiments, on the other hand, are able to avoid thisproblem by employing further techniques and/or algorithms such asantenna travel deviation from straight-line, and/or inverse fast Fouriertransform (IFFT).

According to the present systems and methods, a variety of differentdetection system architectures may be employed for various types ofdetection vehicle. For example, whereas conventional truck rolls areperformed using a land-based automobile, the present embodiments may beeasily configured to operate on aerial vehicles, such as drones. Whereasa land-based automobile is difficult to keep at a constant velocity overan entire cable span of a truck roll, modern drones are capable oftraveling at a relatively constant speed without interruption.Additionally, as the distance between a cable plant and a road may varysubstantially over the span of a truck roll, a drone may be more easilycontrols to maintain a substantially constant perpendicular distancefrom the cable plant, and without significant interruption (e.g.,stopping at traffic devices, slowing from the presence of other vehicleson the road, etc.).

Furthermore, implementation of the present embodiments with respect toan aerial drone may further provide greater flexibility with respect tothe system hardware architecture. Drones tend to be more significantlylimited to the amount of weight that can be carried during operation. Inmany conventional systems though, receivers tend to be heavier (and moreexpensive) than most transmitters. Accordingly, an aerial drone may beadvantageously equipped with a single transmitter, or few lightweighttransmitters, and the receiver may be disposed at the node or hub, orother remote location (e.g., servicing multiple transmitters). That is,the drone need only be equipped with a transmitter (or transmitters)sufficiently capable of transmitting test signal 112 and informationsignal 118, but would not require any receiving capability beyond thatneeded to operate the drone. Some such drones may be programmed toexecute the present embodiments following a cable plant pathwayprogrammed into an autopilot of the drone, and such drones might notneed any receiver ability to operate.

Systems and methods according to the present embodiments thus representsignificant improvements conventional shield break and leakage detectionschemes. Exemplary embodiments of systems and methods for breakdetection are described above in detail. The systems and methods of thisdisclosure though, are not limited to only the specific embodimentsdescribed herein, but rather, the components and/or steps of theirimplementation may be utilized independently and separately from othercomponents and/or steps described herein.

Although specific features of various embodiments may be shown in somedrawings and not in others, such is for convenience only. In accordancewith the principles of the systems and methods described herein, anyfeature of a drawing may be referenced or claimed in combination withany feature of any other drawing.

Some embodiments involve the use of one or more electronic or computingdevices. Such devices typically include a processor, processing device,or controller, such as a general purpose central processing unit (CPU),a graphics processing unit (GPU), a microcontroller, a reducedinstruction set computer (RISC) processor, an application specificintegrated circuit (ASIC), a programmable logic circuit (PLC), aprogrammable logic unit (PLU), a field programmable gate array (FPGA), adigital signal processing (DSP) device, and/or any other circuit orprocessing device capable of executing the functions described herein.The methods described herein may be encoded as executable instructionsembodied in a computer readable medium, including, without limitation, astorage device and/or a memory device. Such instructions, when executedby a processing device, cause the processing device to perform at leasta portion of the methods described herein. The above examples areexemplary only, and thus are not intended to limit in any way thedefinition and/or meaning of the term processor and processing device.

This written description uses examples to disclose the embodiments,including the best mode, and also to enable any person skilled in theart to practice the embodiments, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal language of the claims.

The invention claimed is:
 1. An apparatus for detecting a failure alonga transmission line of a cable plant, comprising: a receiver in operablecommunication with the transmission line upstream from a location of thefailure, the receiver including a processor; and a memory deviceconfigured to store computer-executable instructions, which, whenexecuted by the processor, cause the processor to: receive (i) acontinuous wave (CW) radio frequency (RF) test signal from thetransmission line, the CW RF test signal transmitted from a remotemobile vehicle disposed proximate the cable plant at a separationdistance substantially perpendicular to a lengthwise span of thetransmission line and ingressing the transmission line at the locationof the failure, and (ii) an information signal from the mobile vehicle,the information signal being different from the CW RF test signal andcontaining location and velocity data of the mobile vehicle; and analyzethe received CW RF test signal for frequency spectrum information overtime for phase shift information and Doppler frequency information withrespect to the separation distance from the vehicle to the cable plant.2. The apparatus of claim 1, wherein the receiver is configured toreceive (i) the CW RF test signal through the transmission line from afirst transmitter of the mobile vehicle, and (ii) the information signalfrom a second transmitter of the mobile vehicle.
 3. The apparatus ofclaim 2, wherein the first transmitter includes a first antenna, whereinthe second transmitter includes a second antenna, and wherein the firstantenna is separate from the second antenna.
 4. The apparatus of claim1, wherein the mobile vehicle is a land-based automobile.
 5. Theapparatus of claim 1, wherein the mobile vehicle includes a handheldelectronic device.
 6. The apparatus of claim 1, wherein the mobilevehicle includes an aerial vehicle.
 7. The apparatus of claim 6, whereinthe aerial vehicle is an aerial drone.
 8. The apparatus of claim 7,wherein the aerial drone includes an autopilot module capable of beingprogrammed with executable instructions that, when executed by aprocessing module disposed within the aerial drone, enable the areadrone to travel along the lengthwise span of the transmission line at asubstantially constant aerial speed, and wherein the perpendicularseparation distance between the aerial drone and the transmission lineremains substantially constant over the lengthwise span.
 9. Theapparatus of claim 2, wherein the information signal from the secondtransmitter includes longitude and latitude data obtained from a GPSunit disposed within the mobile vehicle.
 10. The apparatus of claim 9,wherein the receiver is further configured to receive the longitude andlatitude data periodically from the second transmitter on a continualbasis.
 11. The apparatus of claim 10, wherein the receiver is furtherconfigured to receive updated longitude and latitude data between 10 and100 times every second.
 12. The apparatus of claim 9, wherein thereceiver is further configured to receive, within the informationsignal, stored longitude and latitude data obtained from the GPS unitwith respective associated timestamps from a memory unit disposed withinthe mobile vehicle.
 13. The apparatus of claim 12, wherein the receiveris further configured to receive, from the second transmitter, thelongitude and latitude data stored in the memory unit as download data.14. The apparatus of claim 1, wherein the receiver is further configuredto receive the CW RF test signal within the UHF frequency range.
 15. Theapparatus of claim 1, wherein the CW RF test signal includes at leastone of a continuous wave chirp and a pseudo-noise sequence.
 16. Theapparatus of claim 1, wherein the receiver is further configured toreceive the CW RF test signal as multiple simultaneously-transmittedfrequencies.
 17. The apparatus of claim 1, wherein the cable plant isone of an indoor plant and an outdoor plant.
 18. A method for detectinga shield break along a transmission line, the method comprising thesteps of: receiving (i) a continuous wave (CW) test signal from thetransmission line, the CW test signal transmitted from a remote mobilevehicle traveling proximate the cable plant at a separation distancesubstantially perpendicular to a lengthwise span of the transmissionline, the CW test signal ingressing the transmission line at the shieldbreak, and (ii) a periodic information signal from the mobile vehicle,the information signal being different from the CW test signal andcontaining location and velocity data of the mobile vehicle; andanalyzing the received CW test signal for frequency spectrum informationover time for phase shift information and Doppler frequency informationwith respect to the separation distance from the vehicle to the cableplant.
 19. The method of claim 18, further comprising a step ofcalculating, to mitigate a risk of a false image between the first andsecond transmitters, at least one of (i) an inverse Fourier transform,and (ii) an antenna travel deviation from straight-line.
 20. The methodof claim 18, wherein the periodic information signal contains updatedlocation and velocity information about the mobile vehicle, wherein theCW test signal is received from a first transmitter of the mobilevehicle, wherein the periodic information signal is received from asecond transmitter of the mobile vehicle different from the firsttransmitter, and wherein the received CW test signal analyzed togetherwith the updated location and velocity information from the periodicinformation signal to determine the Doppler frequency spectrum of themobile vehicle at a particular velocity with respect to the separationdistance from the transmission line.